JP2001021319A - Method and instrument for measuring eccentricity of continuous paper roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the eccentricity of a continuous paper roll in a non-contacting state without man power by taking the picture of the whole end face of the paper roll with a photographing means and processing the taken picture. SOLUTION: A camera 4 which is the photographing means of an eccentricity measuring instrument is moved upward, downward, leftward, and rightward by means of actuators 5 and 6 in accordance with photographing positions. The camera 4 takes the picture of the whole end face of a continuous paper roll 1 at a position where the optical axis of the camera 4 roughly lies upon the axial line of the core 2 of the roll 1. Successively, the center of the core 2 is found by processing the taken picture of the core 2 and the maximum value and minimum value of the distance between the center of the core 2 of the roll 1 and one point on the outer peripheral line of the roll 1 are found. The eccentricity of the roll 1 is measured from the difference between the maximum value and minimum value. When a digital camera having a large number of picture elements is used, in addition, the structure of the instrument becomes simpler and the measuring time can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring a roll of paper roll manufactured at a paper mill.

[0002]

2. Description of the Related Art In a paper mill, in order to improve the productivity of paper, the paper is usually made in a width of 4 m or more and wound up in a roll form at the exit of the paper machine. Such wide rolls of paper rolls have problems in transportation, the width of paper processing machines such as printing machines for consumers, etc. Cannot be shipped to factory. Therefore, the paper mill cuts it into a suitable small width with a slitter, shortens the winding length if necessary, and rewinds it into a small roll of a size suitable for the processing machine such as the printing machine of the customer before shipping. I do. And
When rewinding into a small volume, a paper tube (core) is used as the core.

[0003]

A roll of take-up paper (hereinafter simply referred to as a paper roll) which has been rewound into a small roll is usually supplied to a printing machine in a printing factory while rewinding it in its original shape. . However, if the cross-sectional shape of the take-up paper roll is not a perfect circle and is eccentric, it has an adverse effect such as fluttering, paper cutting, and printing misalignment in the printing press. Therefore, in the paper mill, the eccentricity of each rolled paper is measured, and only the paper having the eccentricity less than a certain value is shipped.

The measurement of the amount of eccentricity is usually performed by a manual method described below. That is, a cylindrical or conical chucking hardware called a nose is inserted into a core (paper tube) of a take-up paper roll, and a graduated scale is rotated around the core to rotate the scale so that the outer periphery of the take-up paper roll is rotated. The radius from the center is measured over the entire length, and if the difference between the maximum value and the minimum value is equal to or more than a certain value, the shipment is stopped as a defective product.

However, the above-described manual method requires much time and labor, and requires a gap between the nose and the core for rotating the nose. A large gap causes a measurement error, and a small gap causes a measurement error. There is a problem that the rotation of the nose cannot be performed smoothly and the measurement work is stagnated.
Further, since the radius is measured by visually checking the scale, there is also a problem that a human measurement error occurs and the defective paper roll is overlooked.

[0006]

The first technical means for achieving the above object will be described below. First, a roll paper roll supporting means which can be mounted so that the axis of the paper tube of the roll paper roll having a different diameter to be used for measurement is oriented in a substantially constant direction is prepared, and the roll placed on the supporting means is provided. An optical system photographing means (hereinafter, also simply referred to as photographing means) capable of keeping the entire end face of the paper roll in the photographing range is prepared. Further, the photographing means is attached to an elevating device capable of moving up and down such that its optical axis is substantially overlapped with the axis in accordance with the position of the axis of the paper tube of the take-up roll used for measurement.

Then, an image of the entire end surface of the take-up roll is taken by the take-up means at a position where the optical axis of the take-up means substantially overlaps with the axis of the paper tube of the take-up roll. Subsequently, the photographed image of the paper tube is subjected to image processing to obtain the center of the paper tube, and the maximum value and the minimum value of the distance between the paper tube center of the take-up paper roll and one point on the outer peripheral line are obtained. The eccentricity of the roll of paper is measured from the difference between the maximum value and the minimum value.

As described above, first, the entire end face of the take-up paper roll is photographed by the photographing means, and the center position of the end face of the paper tube of the take-up paper roll (or the base in the case of a paper tube with a cap) is obtained. Next, the maximum value and the minimum value of the distance between the center position and a point on the outer peripheral line of the end surface of the take-up paper roll (hereinafter, also simply referred to as the outer peripheral line) are determined, and the difference between the maximum value and the minimum value is calculated. Defined as the amount of eccentricity of the paper roll. The eccentricity defined above is the same as the definition of the eccentricity in the prior art using the nose described above. When photographing the entire end surface of the take-up roll, the photograph is taken from a position where the axis of the paper tube of the take-up roll substantially coincides with the optical axis of the photographing means.

When continuously measuring the eccentricity of a take-up roll successively conveyed by a conveyer, various kinds of conveyers are used as roll support means for conveying the take-up paper roll and stopping and supporting the roll during measurement. Various means or supporting means are conceivable. For example, using a transport conveyor as shown in FIG. 5, temporarily suspending the transport means at a predetermined position where the end face of the roll of paper roll can be clearly photographed at the time of measurement. Can be. This conveyor travels from the near side of the drawing to the back side in the drawing, and conveys the take-up paper roll in its axial direction. The web roll placed on the conveyor stops at a predetermined position of the measuring device.

A camera 4 as a photographing means is moved by actuators 5 and 6 in the vertical and horizontal directions according to the photographing position. The photographing means and the actuator 5 for moving the position of the photographing means are automatically retracted to the right while the web roll is running. The conveyor surface is formed in a concave shape corresponding to the bottom surface of the take-up paper roll, and the take-up paper roll is always placed at a position symmetrical with respect to the center line M in the width direction of the conveyor. With a structure that can be moved in parallel with the center line M, the actuator 5 can be used at the time of photographing the end face of the web roll.
Can be raised and lowered according to the diameter of the take-up paper roll, and the optical axis of the photographing means can be stopped at a predetermined position where it can be substantially overlapped with the axis of the paper tube of the take-up paper roll.

[0011] Further, as a paper roll support means,
Using a rotating roll type conveyor as shown in Fig. 2, the roll of paper is transported in a direction perpendicular to the axial direction of the roll of paper, and the end face of the roll of paper is clarified when measuring the amount of eccentricity. The transporting means may be temporarily stopped at a predetermined position where photographing is possible. The rotating roll conveyor can support the roll of paper with two supporting rolls 3 (3A, 3B) adjacent to each other as a fulcrum, so that if the roll is stopped at a predetermined position, the actuator 5 is wound. By taking up and down according to the diameter of the take-up roll, it is possible to take a picture such that the optical axis of the photographing means substantially overlaps with the axis of the paper tube of the take-up roll. FIG. 3 is a side view of the apparatus of FIG.
The front and rear rotating rolls are not shown.

When the web roll is supported by the two support rolls 3A and 3B, the axis of the paper tube of the web roll is substantially parallel to the axis of the support rolls 3A and 3B. Therefore, if the optical axis of the photographing means is installed so as to be parallel to the axis of the support roll and at the same distance from the axes of the two support rolls, any size of the take-up paper roll can be used. Since the axis of the paper tube is substantially parallel to the optical axis of the photographing means, it is possible to photograph the end face of the take-up paper roll from a substantially constant direction, although the height of the photographing position is different. The height of the photographing position is adjusted by the actuator 5 to a height at which the axis of the paper tube and the optical axis of the photographing means substantially overlap.

When the paper roll is not on a conveyor but on a flat floor or slope and is sequentially kicked out by a pusher, a pair of support rolls 3A and 3B also serving as a paper roll stopper are provided. ,
If the height-adjustable photographing means as described above is provided at that position, the end face of the take-up paper roll can be photographed from a substantially constant direction, similarly to the case where a rotary roll type conveyor is provided.

Further, a function as a stopper for stopping the roll of the roll of paper roll by raising one of the two rolls on the downstream side is provided, and a function of stopping the rotation of the roll of the roll of paper. be able to. If the take-up paper roll is a perfect circular cylinder, the axis of the paper tube passes through the midpoint of the distance between the two support rolls 3A and 3B and connects the two support rolls. Orthogonal to a straight line. The support rolls 3A and 3B need not have the same diameter, but usually have the same diameter, and
Install horizontally with respect to the direction of rotation. The support roll having the same diameter is installed horizontally with respect to the axial direction and the rotation direction, and if the take-up paper roll placed thereon is a perfect circular cylinder, the paper tube of the take-up paper roll is The axis intersects a vertical line passing through the midpoint of the distance between the two support rolls.

If the support rolls 3A and 3B having the same diameter are installed horizontally in both the axial direction and the rotation direction, in the case of an eccentric winding paper roll, the axis of the paper tube is slightly shifted and the axis of the support roll is shifted. , The axis of the paper tube of the take-up roll may not intersect a vertical line passing through the midpoint of the distance between the two support rolls, but the error is slight and negligible. belongs to. Therefore, the support rolls 3A and 3B are installed horizontally with respect to the axial direction and the rotation direction, and the actuator 5 for raising and lowering the photographing means is parallel to a vertical line passing through the midpoint between the axes of the two support rolls 3A and 3B. If the actuator 5 is moved up and down in accordance with the diameter of the take-up roll, and the optical axis of the photographing means is stopped at a predetermined position substantially overlapping with the axis of the paper tube of the take-up roll, The end face of the take-up roll can be photographed at a position where the optical axis of the photographing means substantially overlaps with the axis of the paper tube of the take-up roll.

In order to calculate the eccentricity of the take-up paper roll, first, the center position of the end of the paper tube captured by the photographing means is obtained. For that purpose, it is necessary to digitize the image data of the paper tube obtained by the photographing means and to calculate it quickly by a computer. To digitize an image, it is convenient to use XY plane coordinates centered on a predetermined point during imaging. When using a digital camera for the photographing means, the pixels are arranged in a square pattern on the imaging surface of the digital camera,
The XY plane coordinates are assigned to each of the pixels, and the image of the paper tube is stored as numerical data of the light and dark gradations detected by these pixels. By performing image processing on these numerical data by a computer, the coordinates of the outer peripheral line of the end face of the paper tube and the center of the paper tube can be obtained.

A method for obtaining the center coordinates of the paper tube is, for example, as follows.
Two points are selected on the image of the outer peripheral line of the paper tube end face, and a straight line orthogonal to the middle point of the straight line connecting the two points is considered. Since the paper tube is considered to be a perfect circle, the center of the paper tube is on the straight line. Therefore, two points are selected again on the image of the outer peripheral line of the end face of the paper tube at another position, and a straight line orthogonal to the middle point of the straight line connecting the two points is obtained. The coordinates of the intersection of the straight line and the straight line Is the center coordinate of the paper tube.

In order to ensure accuracy, the positions of the two points to be selected are made different, and the calculation of the center point is performed several times.
The average value of the calculation results may be used as the center coordinates of the paper tube.
These calculations may be performed by using known image processing software. Instead of using a digital camera, it is possible to convert an image obtained by an analog imaging means into digital data and indirectly determine the center coordinates of a paper tube, but it is preferable to use a digital camera that can directly obtain numerical data .

After the numerical calculation of the coordinates of the center Q (Xk, Yk) of the paper tube is completed, the center Q (Xk, Y
From k), the maximum value and the minimum value of the distance to one point on the outer periphery of the end surface of the take-up paper roll are determined. The coordinate data of the outer peripheral line of the end surface of the take-up paper roll photographed by the digital camera is a circle that is almost a perfect circle formed by a set of a large number of coordinate points, and the center coordinates Q (Xk, Y
It is not necessary to determine the distance to the point Lm (Xm, Ym) divided into n parts at an appropriate angular interval around the center coordinate Q.
m) (where m = 1, 2, 3,..., n) and the center coordinate Q
The distance Rm from (Xk, Yk) may be obtained. To simplify these calculations, the coordinates (Xk,
If Yk) is coordinate-corrected and set to the origin (0,0), the calculation is simplified.

That is, the center Q of the paper tube of the take-up paper roll
The distance Rm between (Xk, Yk) and one point Lm (Xm, Ym) on the outer circumference of the take-up paper roll is represented by a general formula: Rm = ((Xk−Xm) ² + (Yk−Ym) ² )
^1/2 (where m = 1, 2, 3,... N), but the coordinate is corrected to a coordinate system with the coordinates (Xk, Yk) of the center Q of the paper tube as the origin (0, 0). Then, Rm = ((Xm) ² + (Ym) ² ) ^1/2 (where m = 1, 2, 3,... N).

As described above, a photograph is taken at a position where the optical axis of the photographing means for photographing the end face of the take-up roll substantially overlaps the axis of the paper tube of the take-up roll, and the eccentricity of the take-up roll is determined from the image. Having described the apparatus and method to be sought, the second apparatus and method that does not require overlapping the axes will now be described. According to the second apparatus and method, since it is not necessary to overlap the axes, the measuring operation is simple and the measuring apparatus is also simple.

According to a second aspect of the present invention, there is provided a roll paper roll supporting means which can be mounted so that the axes of the paper tubes of the roll paper rolls having different diameters are substantially in the same direction, and is mounted on the support means. And an optical system photographing means fixed at a position where the entire end surface of the take-up paper roll can be accommodated in the photographing range, and the optical axis of the optical photographing means is provided to the take-up paper roll support means. The axis of the paper roll of the placed roll is substantially parallel to the axis of the paper roll, and the center of the paper roll of the roll is fixed to a position where the image is taken in the vicinity of the Y axis on the XY plane of the image receiving surface, An image of the entire end surface of the take-up paper roll is photographed by the photographing means, and the image of the photographed oval image of the take-up paper tube is obtained to determine the center of the take-up tube. Process the elliptical image of the outer To correct the circular image when the end surface of the take-up paper roll is photographed from almost straight ahead, and the maximum value and the minimum value of the distance between the center of the paper tube of the take-up paper roll and one point on the corrected outer peripheral line. This device measures the amount of eccentricity of the take-up paper roll from the difference from the value.

The web roll support means on which the web roll to be subjected to the measurement is placed may be substantially the same as the above-described first apparatus. The photographing means is fixed such that the center of the paper tube of the take-up paper roll is photographed substantially at the center of the image receiving surface. There are various types of rolls of paper roll to be used for measurement within a certain range, but it is necessary to fix and install the roll at a position where the image does not deviate from the image receiving surface of the photographing means even if the diameter changes. is there.

Further, it is necessary to be able to photograph the entire end face of the roll of the roll having the smallest diameter. Further, since the photographing means is fixed, the end of the roll of the roll is photographed obliquely. It is necessary to correct the elliptical image of the end face like a circle taken directly from the front. In order not to complicate the correction calculation, and to reduce the error in the correction calculation, the optical axis of the photographing means should have an average diameter of the roll of paper roll used for the measurement. When placed on top, it is desirable to fix the roll at an angle substantially parallel to the axis of the paper tube of the roll.

In the case of using an optical photographing means, a photographing means using a lens which does not cause distortion in the peripheral portion of the image receiving surface is also known. Therefore, it is desirable that the image of the take-up paper roll is always formed at the center of the image receiving surface of the photographing means even if the diameter of the take-up paper roll used for measurement changes. Therefore, when the take-up paper roll is placed on the pair of support rolls 3A and 3B as the roll support means, the most desirable fixing position and fixing angle of the photographing means are determined by the distance between the axes of the support rolls 3A and 3B. On a straight line passing through the points, the optical axis of the photographing means having an average diameter of the roll of paper roll to be measured and having a perfect circular end face was placed on the support means. At this time, it is desirable to fix the roll at the position and angle where the axis of the paper tube and the optical axis of the paper roll overlap.

When the difference between the maximum diameter and the minimum diameter of the paper roll used for the measurement is extremely large, when the paper roll having a size intermediate between the maximum diameter and the average diameter is placed on the support roll. A photographing means is provided at a position where the axis of the paper tube of the take-up paper roll and the optical axis substantially overlap with each other, and further, the take-up paper roll having an intermediate size between the minimum diameter and the average diameter is placed on the support means. When placed on the roll, another photographic means is provided at a position where the axis of the paper tube of the take-up paper roll and the optical axis substantially overlap with each other, and two photographings are performed according to the diameter of the take-up paper roll. You may use them properly. In some cases, the number of photographing units may be further increased.

The difference between the first device and the second device has been described above. Next, the principle of measuring the amount of eccentricity by the second device will be described. FIG. 6 is a diagram illustrating an example of the second device.
The support means for the web roll is a pair of support rolls 3A and 3B as in the first method. The photographing means 4 is fixed at a position where an image of an end face of the roll 1 having an average diameter, the roll 1A having the maximum diameter, and the roll 1B having the minimum diameter can be photographed among the rolls used for measurement. Have been.

When the roll 1 having an average diameter of the roll of paper to be measured is placed on the supporting means, the optical axis of the photographing means and the optical axis of the roll of paper 1 substantially overlap. , The left and right photographing means are fixed. There are various types of rolls for the rolls to be used for the measurement. When the rolls are placed on the support rolls 3A and 3B, the axes of the paper tubes of the respective rolls are slightly shifted. It can be regarded as substantially parallel to the optical axis of the photographing means.

The photographing means 4 is a digital camera in which a number of pixels are arranged in a grid on an image receiving surface, and each pixel has
XY coordinates are given with the origin substantially at the center of the image receiving surface. The angle of the digital camera is adjusted and fixed so that the X axis of the XY coordinates is substantially parallel to a straight line connecting the support rolls 3A and 3B. Therefore, the center Q (Xk, Xk) of the paper tube in the image of the paper rolls 1, 1A, 1B.
Yk) is photographed on the Y-axis or in the vicinity of the Y-axis, though there is some deviation.

When the digital camera 4 takes an image of the end face of the roll 1A having a diameter larger than the average diameter or the end face of the roll 1B having a diameter smaller than the average diameter, the images of the end face of the paper tube and the outer peripheral line of the roll are shown in FIG. As shown by the solid line in FIG. 7, only the Y-axis direction has a reduced elliptical shape. Since the original shape of the end face of the paper tube can be regarded as a perfect circle,
If the end face of the take-up paper roll is photographed from the front, that is, the optical axis of the digital camera 4 coincides with the axis of the paper tube 2, the image of the paper tube is a perfect circle as shown by the dotted line in FIG.
Therefore, the image of the paper tube indicated by the solid line in FIG. 7 is reduced in the Y-axis direction, and the reduction ratio is determined by the short-axis length ff ′ (the maximum diameter in the Y-axis direction) and the long-axis length ee ′ ( (Maximum diameter in the X-axis direction). Then, the center coordinates Q (X
k, Yk) are the coordinates of the intersection of the major axis ee 'and the minor axis ff'. Since the positions and lengths of the short axis ff ′ and the long axis ee ′ on the image receiving surface of the digital camera can be calculated by processing the image of the end face of the paper tube, r = the short axis length f
f ′ / long axis length ee ′ can be easily calculated, the center coordinates Q (Xk, Yk) of the ellipse, which is the intersection of the short axis and the long axis, can be easily calculated, and the center coordinates Q (Xk, Yk) of the ellipse can be calculated. ) Can be regarded as the center of the paper tube without having to calculate by correcting the elliptical image of the paper tube into a circular image.

Like the image of the end face of the paper tube, the image of the outer periphery of the take-up paper roll has the same ratio r, and only in the Y-axis direction,
Since the scale is reduced, the Y coordinate of each point constituting the image of the end face of the paper tube is enlarged by 1 / r times with respect to the X axis to enlarge the roll into a circular image taken directly from the front. can do. After completion of the correction, as in the case of the first apparatus, one point Lm (Xm, Ym) of the outer peripheral line of the take-up paper roll and the center coordinates Q (Xk, Y
k) to calculate the maximum length and the minimum length of the distance Rm,
The difference between the maximum value and the minimum value can be used as the amount of eccentricity of the paper roll. In addition to the above, there is a method of correcting the elliptical image of the outer peripheral line into a circular image taken from almost directly in front of the end surface of the take-up paper roll, but the description is omitted.
In the present invention, any method may be used for the above correction as long as the position coordinates of the center of the paper tube are not changed. In the above calculation, after photographing the image of the take-up paper roll, the origin of the XY coordinates of the image receiving surface of the photographing means is set to the center coordinate Q of the ellipse.
If the above calculation is performed after the coordinate correction to make it coincide with (Xk, Yk), the subsequent calculation is simplified, as in the case of the first device.

Note that the X-axis on the image receiving surface is
Even if the digital camera is not fixed so as to be parallel to the straight line connecting A and 3B, by correcting the angle of the coordinates,
Although the amount of eccentricity of the paper roll can be calculated, the calculation becomes complicated and takes time. If the digital camera is fixed so that the X axis is parallel to the straight line connecting the support rolls 3A and 3B, when the coordinates of the major axis of the elliptical image are to be obtained, two points on the ellipse are converted to the X axis. Consider a straight line that intersects with a parallel straight line, and since the maximum value of the distance between the two points is the major axis length,
Calculation is easy. Similarly, the short axis length and the center of the ellipse can be calculated by a simple calculation.
It is desirable to fix the digital camera at an angle parallel to the straight line connecting A and 3B. In the second apparatus described above, an analog camera can be used instead of the digital camera, but the subsequent processing becomes complicated as in the case of the first apparatus.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In calculating a distance between a point on the outer peripheral line of a take-up paper roll and a center coordinate Q (Xk, Yk), the center Q of the paper tube is defined as an origin P (0, 0). )
When considering in a coordinate system where coordinates are corrected, each point L equally divided into n
The coordinate (Xm, Ym) of m is a straight line y = tan passing through the origin.
2π (m / n) · x (where m = 1, 2, 3, 4, 5,
.., n) and the coordinates of the intersection of the outer circumference of the take-up roll, but the portion of the take-up roll in contact with the support roll is deformed by its weight, so the data of the deformed portion is excluded. In such a case, it is possible to exclude the data of the deformed portion by limiting the value of m to a certain range. Further, since the contact point with the roll can be recognized by image processing, the coordinates of the intersection of the outer peripheral line near the contact point and the straight line y = tan2π (m / n) · x can be excluded.

When the coordinates of the intersection Lm between the outer line of the take-up paper roll, the straight line y = tan2π (m / n) · x passing through the origin P (0,0) and the outer line of the paper tube are obtained. In some cases, abnormal values may occur due to minute deformation of the skin of the take-up paper roll or an influence of a change in illumination. As a countermeasure to reduce the measurement error, if the slope of the straight line y is changed little by little around 2π (m / n) and the intersection of the approximate curve connecting the coordinates of the intersection and the straight line y is calculated, the influence of the abnormal value is reduced. be able to.

In the first method, since there are various types of diameters of the paper roll, if the height position of the roll supporting means is fixed, if the diameter of the paper roll to be measured changes. , The center height of the paper tube changes. Said,
If the photographing means is freely movable up and down, it is possible to cope with a change in the height of the paper tube center. At that time, in order to bring the position of the photographing means closer to the center height of the paper tube, the approximate diameter of the roll of rolls is measured in advance. In addition, since there are various widths of the take-up roll, the roll can be moved back and forth so that the distance from the lens of the photographing means can be kept constant, and the position of the end face of the take-up roll can be roughly adjusted in advance. Measure it. For these measurements, for example, an ultrasonic sensor or an infrared sensor can be used.

FIG. 2 is a side view for explaining the schematic structure of the eccentricity measuring apparatus according to the first embodiment of the present invention, and has a symmetric structure. FIG. 1 is a side view for explaining the structure of a part of FIG.
Fig. 3 is a measurement diagram of Fig. 2. The take-up paper roll 1 used for measuring the amount of eccentricity is formed by being taken up by a paper tube 2, and the width and the take-up length are in accordance with a request of a consumer. The take-up paper roll 1 is placed on and supported by two support rolls 3A and 3B which are installed horizontally.

The photographing means includes a paper core 2 of a take-up paper roll 1.
Is provided with a digital camera 4 having an optical axis parallel to the axis of the paper roll of the take-up paper roll. This digital camera 4 has a first actuator 5
Thus, the distance supported along a vertical line passing through the midpoint of the distance between the support roll axes can be raised and lowered accurately. The approximate diameter of the paper roll is measured in advance by a distance sensor 8 using infrared rays or ultrasonic waves, and a digital camera is set so that an image can be taken at a position where the axis of the paper tube and the optical axis of the digital camera 4 almost overlap. 4 is instructed to the first actuator 5.

The upper part of the first actuator 5 is supported by a second actuator 6, and the first actuator 5 is movable along a direction parallel to the axial direction of the supporting rolls 3A and 3B. I have. Accordingly, the movement of the actuators 5 and 6 allows the digital camera 4 to approach and separate from the end of the paper tube 2 so that the end can be reliably contained in the photographing range. Further, as described above, the first actuator 5 is provided with the distance sensor 7 such as an infrared sensor for detecting the distance to the end surface of the web roll 1, and the upper portion of the web roll 1 is roughly A distance sensor 8 for detecting the outer diameter of the roll is provided. The distance sensor detects the approximate outer diameter of the roll of paper roll, and the arithmetic unit (not shown) calculates the elevation distance of the digital camera. You.

The elevating distance is calculated so that an image of the paper tube can be taken at substantially the center of the image receiving surface of the digital camera.
This is a calculation for raising and lowering the digital camera. The reference position of this elevation distance may be set anywhere, for example,
Based on the position where the center of the paper tube of the roll paper roll to be measured is approximately the average size is taken at the center of the image receiving surface of the camera as a reference, a distance above the position is a plus distance, and a value below the position is a minus. If the distance is used, even if the diameter of the roll of paper roll used for the measurement changes, the amount of elevation can be reduced.

In FIG. 3, a roll 1A having the largest diameter that can be measured by the eccentricity measuring device is shown in FIG.
The paper roll 1B having the smallest diameter is also shown. These rolls of paper are rolled over the pair of support rolls 3.
When the paper roll is placed on the rolls A and 3B, the center of the paper tube 2 of the take-up roll 1 is located above the midpoint of the distance between the axes of the support rolls 3A and 3B, regardless of the size of the outer diameter. Will be. The photographing means of the winding eccentricity measuring device is disposed at both ends of the roll of paper roll. For this reason, the eccentricity measurement can be performed at both ends of the paper roll. If the indicating rolls 3A and 3B are installed horizontally, the optical axis of the photographing means will be a vertical center line passing through the midpoint of the distance between the axes of 3A and 3B according to the diameter of the take-up roll. Move along M.

When the eccentricity is measured with the take-up paper roll at a position on the conveyor, the measurement can be performed in the same manner as on the support rolls 3A and 3B, as shown in FIG. Similarly, when the roll of paper is transported in the axial direction of the roll of paper, the amount of eccentricity can be measured at both ends of the roll of paper.

The position data captured by the digital camera 4 and data relating to the elevation distance of the digital camera 4 and the like are input to an arithmetic unit (not shown) and used for calculating the above-mentioned and later-described mathematical expressions. The operation of the eccentricity measuring device for the take-up paper roll according to this embodiment configured as described above will be described below with reference to FIG.

The take-up paper roll 1 used for the measurement is fed to the eccentricity measuring device by a transport device (not shown), and is placed on the support rolls 3A and 3B. The center of the end face of the paper tube 2 is located substantially on the vertical line at the midpoint of the distance between the axes of the support rolls 3A and 3B. Based on the data of the distance sensor 8,
Activating the first actuator 5 to move the camera 4
The paper tube is moved up and down to a height position where the axis of the paper tube substantially overlaps the optical axis of the camera 4. At this time, the movement amount of the digital camera 4 is measured as a distance from the reference position. This measurement can be easily recognized by, for example, counting the number of pulses of the first actuator 5 using a pulse motor or providing an encoder or the like. Next, the second actuator 6 is operated to position the digital camera 4 at a position where an image on the paper tube 2 can be captured. At this time, the digital camera 4 is referred to by referring to the distance to the take-up paper roll obtained by the distance sensor 7.
To move.

When the image of the end face of the paper tube 2 is captured by the digital camera 4, the coordinates (Xk, Yk) of the center Q of the paper tube 2 are substantially circular, and the position data of the image of the paper tube is obtained. It can be calculated by the image processing method described above. Before photographing the image of the end face of the paper tube, the origin of the coordinate system of the photographing means can be arbitrarily determined. For example, it may be the lower left corner of the image plane of the digital camera or another corner. However, as described above, after the coordinates (Xk, Yk) of the center Q of the paper tube are calculated, the coordinates are corrected by the arithmetic unit, and the coordinates of the center Q of the paper tube are set to the origin P of the photographing means.
If the coordinates are made coincident with the coordinates of (0, 0), the subsequent calculation is facilitated.

Next, the principle of calculating the amount of eccentricity of the paper roll used for measuring the amount of eccentricity by the eccentricity amount measuring apparatus described above will be described. As described above, first, assuming that the origin of the coordinate system of the photographing means is P (0,0), the center coordinate Q of the paper tube is
(Xk, Yk) is obtained. Center coordinates Q (Xk, Y
In addition to the method described above, k) can be obtained by selecting three points from the outer circumference of the paper tube and obtaining the equation of a circle passing through the three points. If the three points are appropriately changed, the above calculation is repeated several times, and the average value is adopted, the error becomes smaller.

Next, 2π passes through the coordinates Q of the image of the center of the paper tube.
/ n straight lines with different slopes ym = tan2π (m / n)
Intersection Lm between x and the image of the outer circumference circle of the end of the roll of paper roll
(Xm, Ym) is obtained. (However, m = 1, 2,
3. . . n) Since the center Q and the origin of the paper tube are matched by the coordinate correction, Rm = ((Xm) ² + (Ym) ² ) ^1/2 (where m = 1, 2, 3,...) n)

Although the measurement error decreases as n increases,
It may be roughly 10 or more. Also, as mentioned above,
When an intersection Lm between the outer periphery of the roll of paper roll and the straight line ym is obtained, an error may occur if only one measurement value is obtained. Therefore, several nearby points are measured (for example, ym = (2π / n)).
When the intersection with x is obtained, if the intersection with y'm = (2π / n ± 0.01) × x having a slightly different slope from the straight line is also obtained and averaged, the error is reduced. . In this way, the difference between the maximum value and the minimum value of Rm is obtained and used as the amount of eccentricity of the paper roll.

The intersection point Lm (Xm, Ym) of the image of the center coordinate of the take-up paper roll and the outer peripheral circle of the end of the take-up paper roll
The numerical data on which m) is calculated is preferably data obtained from the same image. For example, when taking an image of a paper tube, a larger image can be obtained by taking a digital camera closer to the take-up paper roll than when taking an image of the outer peripheral line of the end surface of the take-up paper roll. The accuracy of calculating the coordinates of the center of the tube is also increased. The axis of the paper tube is the optical axis (the axis passing through the center of the lens and orthogonal to the lens)
If the camera is completely overlapped without any deviation, the coordinates of the center of the paper tube will not change even if the camera is moved in the optical axis direction with respect to the end surface of the take-up paper roll, but there is no problem. If they do not overlap with the optical axis, large errors may occur in the calculation results. In addition, instead of moving the digital camera in the optical axis direction, using a telephoto lens or a zoom lens to capture images of the paper tube end surface and the outer surface of the take-up paper roll at different magnifications, the same error as described above may occur. Care must be taken because

In the operation described above, the position data and the amount of movement of the actuator captured by the digital camera 4 are input to an arithmetic processing unit (not shown).
Since the calculation is performed by the processing device, the operation is facilitated by displaying the image captured by the camera 4 on a monitor and performing the work while visually recognizing the monitor.

[0050]

FIG. 8 shows an apparatus for measuring the eccentricity of a paper roll according to the first aspect of the present invention, the maximum eccentricity when the eccentricity is measured by a conventional measuring method, and the measurement required. Shows the results for time. In the same figure, Example 1 shows the result of measurement on a paper roll 1A having a diameter of 1,100 mm using the eccentricity measuring device for the paper roll according to the first method of the present invention. 2 shows the result measured about the roll paper roll 1B whose diameter is 860 mm.

In Comparative Examples 1 and 2, the amounts of eccentricity of the take-up paper roll 1A and the take-up paper roll 1B were measured by a manual operation using a conventional nose. The results are shown. Comparative Examples 3 and 4 show the results of carefully measuring the eccentricity of the take-up paper roll 1A and the take-up paper roll 1B by hand using a nose that is precisely fitted to the paper tube 2, respectively. .

When the measurement results shown in FIG. 8 are compared, the maximum eccentricity measured by the eccentricity measuring apparatus according to the present invention is the maximum eccentricity measured almost accurately by the hands shown in Comparative Examples 3 and 4. The value was close to the core weight, and almost satisfactory data could be obtained. In addition, the measurement time can be reduced to about one-fifth that of the conventional method, which is advantageous in terms of the measurement time, and the total number of rolls supplied can be measured.

[0053]

As described above, according to the eccentricity measuring device for a take-up paper roll according to the present invention, the photographing means for photographing the paper tube is provided, and the arithmetic processing is performed from the image captured by the photographing means. Since the eccentricity of the take-up paper roll is calculated by the apparatus, the eccentricity can be measured without manual operation, and the occurrence of an artificial measurement error can be eliminated. In addition, since the measurement can be performed without contacting the roll of paper, the measurement can be performed smoothly.

In the apparatus according to the first aspect of the present invention, the photographing means is moved by the elevating device, and the photographing is performed from almost in front of the end surface of the take-up paper roll, so that the measurement accuracy is high. According to the second and third aspects of the present invention, since the photographing means is fixed, it is necessary to correct the image of the end surface of the take-up roll as if photographed almost from the front. However, a digital camera having a larger number of pixels is used. Accordingly, the same measurement accuracy as that of the device of the first aspect can be ensured, and since no elevating device is required, the structure is simple and the measurement time can be further reduced. The invention according to claim 4 is an invention in which a digital camera is used as the photographing means.

[Brief description of the drawings]

FIG. 1 is a schematic front view for explaining a schematic structure of an eccentricity measuring device for a take-up paper roll according to claim 1;

FIG. 2 is a schematic front view for explaining a schematic structure of an eccentricity measuring device for a take-up paper roll according to the invention of claim 1;

FIG. 3 is a side view of FIG.

FIG. 4 is a view for explaining the principle of calculating the eccentricity by the eccentricity measuring device for a take-up paper roll according to the present invention.

FIG. 5 is a side view of an application example of the eccentricity measuring device of the paper roll according to the present invention, in which the eccentricity of the paper roll on a conveyor is measured.

FIG. 6 is a schematic front view for explaining a schematic structure of an eccentricity measuring device for a take-up paper roll according to the second and third aspects of the present invention.

FIG. 7 is a diagram for explaining the principle of calculating the eccentricity by the eccentricity measuring device for a take-up paper roll according to the second and third aspects of the present invention.

FIG. 8 is a table for comparing the result measured by the eccentricity measuring device of the roll of paper roll according to the present invention with the result measured by the conventional method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 winding paper roll 1A maximum diameter winding paper roll 1B minimum diameter winding paper roll 2 paper core (paper tube base) 3 support roll 3A support roll 3B support roll 4 photographing means (digital camera) 5 actuator 6 actuator 7 Distance sensor 8 Distance sensor 10 Roll paper conveyor H H Horizontal line M Center line P Origin Q Center of the paper tube of the roll paper used for measurement

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shun Tojo 5-2-1-1, Oji, Kita-ku, Tokyo Nippon Paper Industries Co., Ltd. F-term (reference) 2F065 AA06 AA12 AA17 AA26 AA45 AA48 AA51 BB08 CC00 DD06 EE00 FF04 FF42 FF63 FF67 JJ03 JJ09 JJ26 NN20 PP03 PP15 PP16 QQ03 QQ17 QQ21 QQ24 QQ25 QQ28 QQ42 SS02 SS13 TT02

Claims (5)

[Claims] 1. A take-up paper roll supporting means that can be placed so that the axis of the paper tube of the take-up paper roll having a different diameter is oriented in a substantially constant direction, and a photographing area covering the entire end face of the take-up paper roll placed on the supporting means. 1. Optical system photographing means provided at a position that can be accommodated in Further, the optical photographing means is moved up and down by an elevating device capable of elevating and lowering the optical axis so as to substantially overlap the axis in accordance with the position of the axis of the paper tube of the winding paper roll having a different diameter. 3. an image of the entire end surface of the take-up roll is taken by the take-up means at a position where the optical axis of the optical taking means substantially overlaps with the axis of the paper tube of the take-up roll; 4. Image processing of the taken image of the paper tube to determine the center of the paper tube; An apparatus for measuring the amount of eccentricity of the paper roll from the difference between the maximum value and the minimum value of the distance between the center of the paper core of the paper roll and one point on the outer peripheral line. 2. A take-up roll supporting means that can be placed so that the axis of the paper tube of the take-up roll having a different diameter is substantially constant, and a photographing area covering the entire end face of the take-up roll placed on the supporting means. 1. Optical system photographing means fixed at a position that can be accommodated in Further, the optical photographing means has an optical axis substantially parallel to the axis of the paper tube of the take-up paper roll placed on the take-up paper roll support means, and the center of the paper tube of the take-up paper roll. Is fixed at a position where the image is taken in the vicinity of the Y-axis on the XY plane of the image receiving surface; 3. An image of the entire end surface of the take-up paper roll is photographed by the photographing means, and the image of the photographed oval image of the take-up paper tube is obtained by image processing to determine the center of the paper tube. 4. Correcting the captured elliptical image of the outer periphery of the take-up paper roll into a circular image obtained by photographing the end face of the take-up paper roll almost directly from the front by image processing; An apparatus for measuring the eccentricity of the take-up roll from the difference between the maximum value and the minimum value of the distance between the center of the paper tube of the take-up roll and one point on the outer peripheral line subjected to the correction processing. 3. 1. The web roll is placed on web roll support means that can be mounted so that the axis of the paper tube of the web roll of a different diameter is substantially constant. The optical axis is substantially parallel to the axis of the paper tube of the take-up paper roll placed on the take-up paper roll support means, and the center of the paper tube of the take-up paper roll is on the XY plane of the image receiving surface. 2. photographing the entire end face of the web roll by photographing means fixed at a position photographed in the vicinity of the Y axis; 3. The center of the paper tube is obtained by performing image processing on the photographed oval image of the paper tube of the take-up paper; 4. Correcting the captured elliptical image of the outer periphery of the take-up paper roll into a circular image obtained by photographing the end face of the take-up paper roll almost directly from the front by image processing; Measuring the amount of eccentricity of the take-up roll from the difference between the maximum value and the minimum value of the distance between the center of the paper tube of the take-up roll and one point on the outer peripheral line subjected to the correction processing; Quantity measurement method. 4. The apparatus for measuring the amount of eccentricity of a take-up paper roll according to claim 1, wherein the photographing means is a digital camera. 5. The method according to claim 3, wherein the photographing means is a digital camera.